add cov report

.github/workflows/unittest.yml

@@ -29,4 +29,36 @@ jobs:
         coverage run tests/run.py
     - name: Generate coverage report
       run: |
-        coverage report -m
+        coverage report -m > coverage.txt
+    - name: Update or Post coverage report as PR comment
+      if: github.event_name == 'pull_request'
+      uses: actions/github-script@v3
+      with:
+        github-token: ${{secrets.GITHUB_TOKEN}}
+        script: |
+          const fs = require('fs');
+          const report = fs.readFileSync('coverage.txt', {encoding:'utf8', flag:'r'});
+          const commentIdentifier = '<!-- coverage-comment -->';
+          const commentBody = `${commentIdentifier}\n📊 **Coverage Report**:\n\`\`\`\n${report}\n\`\`\``;
+
+          const issue_number = context.issue.number;
+          const comments = await github.issues.listComments({
+            ...context.repo,
+            issue_number
+          });
+
+          const coverageComment = comments.data.find(comment => comment.body.includes(commentIdentifier));
+
+          if (coverageComment) {
+            await github.issues.updateComment({
+              ...context.repo,
+              comment_id: coverageComment.id,
+              body: commentBody
+            });
+          } else {
+            await github.issues.createComment({
+              ...context.repo,
+              issue_number,
+              body: commentBody
+            });
+          }